OTTAWA — Four months after it was passed by the House of Commons, a bill that would require labour unions to disclose detailed financial information, including how much is spent on political activities, has run into opposition in the Senate.

Bill C-377 is at second reading in the Senate and has already received a negative welcome from a Tory senator. On Tuesday, the Liberal leader in the Senate went a step further, saying the bill, with its “stunning shortcomings and its horrendous drafting,” should be defeated by the upper chamber.

Some of those drafting issues were dealt with by a House of Commons committee studying the bill late last year. It tried to reword parts of the bill to deal with privacy concerns.

But Sen. James Cowan said Tuesday that changes to bill C-377 didn’t go far enough. Quoting from the bill, he argued C-377 is worded in such a way that anyone receiving more than $5,000 from a union — such as a part-time worker or contracted company — would have their personal information publicly posted. He said it gives “absolutely no limit” on information the government could force unions to disclose.

The proposed legislation, if passed, could also apply to an employee association, wording that could ensnare even Merit Canada — an association of construction employees, which is one of the employee groups pushing for passage of C-377.

Sen. James Cowan says the labour-financing bill is part of a Tory government agenda to crack down on its critics.

“American jurist Felix Frankfurter . . . believed that the role of law is to try to build a heaven on Earth. Colleagues, what kind of ‘heaven’ are we being asked to build with Bill C-377? Our new heaven will be a place where if you work for a labour organization, or do business with a labour organization, then you will forfeit basic rights enjoyed by all other Canadians. That is the crux of this legislation,” Cowan argued.

“And why is this being done? I believe the answer can be found in a larger story; one where the Harper government is trying to systematically silence individuals and organizations who dare to challenge it publicly.”

Cowan argued that rather than bring transparency the bill would bury unions in paperwork — along with adding to the Canada Revenue Association’s workload — and effectively silence their voice, invoking arguments from American history that suggested such reporting requirements were “a lot of junk” and aimed at weakening unions.

“Is this what our tax code should be used for? Is this the kind of law we want to be passing? Is this the Harper Conservatives’ view of ‘heaven on Earth?’ ” Cowan said.

“This is the same government that abandoned the mandatory long-form census because it was too intrusive,” Cowan said in a speech to the Senate chamber.

“In this country, we value our privacy. . . . We have laws protecting the right of Canadians to privacy. Yet this bill says: If you work for a labour organization, you lose that right.”

It is not normal for the largely unelected Senate to kill a bill passed by the elected House of Commons.

Four provinces — Ontario, Quebec, Nova Scotia and Manitoba — have also voiced concerns about the bill, saying it could damage their ability to bargain collectively with their public-sector unions. Labour unions have also come out against the bill, which was passed by the Commons in December.

The bill would require all unions and employee organizations to give the Canada Revenue Agency details of all transactions of $5,000 or more, including the names and addresses of the people, groups or organizations that received the money along with reasons for the payments. Unions would also be required to provide the salaries and benefits of offers, directors and trustees, along with a detailed breakdown of the union’s spending on political and lobbying activities.

The information would be publicly posted on the CRA’s website.

Failure to comply would result in a fine of a $1,000 per day.

A Commons committee was told last year that the ongoing cost of administering the program would be about $2 million annually.